Structure of atoms

teaching standard

spatial concepts

Matter is made of minute particles called atoms, and atoms are composed of even smaller components. These components have measurable properties, such as mass and electrical charge. Each atom has a positively charged nucleus surrounded by negatively charged electrons. The electric force between the nucleus and electrons holds the atom together. 178 B (9-12)

atom, force, interaction, mass, measurement, nucleus, small, surround

The atom's nucleus is composed of protons and neutrons, which are much more massive than electrons. When an element has atoms that differ in the number of neutrons, these atoms are called different isotopes of the element. 178 B (9-12)

composition, mass, nucleus, size

The nuclear forces that hold the nucleus of an atom together, at nuclear distances, are usually stronger than the electric forces that would make it fly apart. Nuclear reactions convert a fraction of the mass of interacting particles into energy, and they can release much greater amounts of energy than atomic interactions. Fission is the splitting of a large nucleus into smaller pieces. Fusion is the joining of two nuclei at extremely high temperature and pressure, and is the process responsible for the energy of the sun and other stars. 178 B (9-12)

bond, distance, fission, force, nucleus, scatter, size

Radioactive isotopes are unstable and undergo spontaneous nuclear reactions, emitting particles and/or wavelike radiation. The decay of any one nucleus cannot be predicted, but a large group of identical nuclei decay at a predictable rate. This predictability can be used to estimate the age of materials that contain radioactive isotopes. 178 B (9-12)

decay, emission, nucleus, radiation, rate, wave

Structure and properties of matter

teaching standard

spatial concepts

Atoms interact with one another by transferring or sharing electrons that are furthest from the nucleus. These outer electrons govern the chemical properties of the element. 178 B (9-12)

An element is composed of a single type of atom. When elements are listed in order according to the number of protons (called the atomic number), repeating patterns of physical and chemical properties identify families of elements with similar properties. This 'Periodic Table' is a consequence of the repeating pattern of outermost electrons and their permitted energies. 178 B (9-12)

outer, pattern, representation, spatialization

Bonds between atoms are created when electrons are paired up by being transferred or shared. A substance composed of a single kind of atom is called an element. The atoms may be bonded together into molecules or crystalline solids. A compound is formed when two or more kinds of atoms bind together chemically. 179 B (9-12)

atom, atomicity, bond, composition, crystalline, interaction, pairing

The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them. 179 B (9-12)

Solids, liquids, and gases differ in the distances and angles between molecules or atoms and therefore the energy that binds them together. In solids the structure is nearly rigid; in liquids molecules or atoms move around each other but do not move apart; and in gases molecules or atoms move almost independently of each other and are mostly far apart. 179 B (9-12)

Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, including synthetic polymers, oils, and the large molecules essential to life. 179 B (9-12)

atom, bond, branching, chain, molecule, network, ring

Page 2

Chemical reactions

teaching standard

spatial concepts

Chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. Complex chemical reactions involving carbon-based molecules take place constantly in every cell in our bodies. 179 B (9-12)

cell, scale, surrounding

Chemical reactions may release or consume energy. Some reactions such as the burning of fossil fuels release large amounts of energy by losing heat and by emitting light. Light can initiate many chemical reactions such as photosynthesis and the evolution of urban smog. 179 B (9-12)

emission, urban

A large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Radical reactions control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.

atom, bond, formation, scale, transfer

Chemical reactions can take place in time periods ranging from the few femtoseconds (10**-15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. Reaction rates depend on how often the reacting atoms and molecules encounter one another, on the temperature, and on the properties--including shape--of the reacting species. 179 B (9-12)

distance, encounter, motion, movement, scale

Catalysts, such as metal surfaces, accelerate chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes. 179 B (9-12)

acceleration, adjacency, surface

Motion and forces

teaching standard

spatial concepts

Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. The magnitude of the change in motion can be calculated using the relationship F=ma, which is independent of the nature of the force. Whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object. 179 B (9-12)

direction, force, magnitude, motion, object, opposite

Gravitation is a universal force that each mass exerts on any other mass. The strength of the gravitational attractive force between two masses is proportional to the masses and inversely proportional to the square of the distance between them. 180 B (9-12)

distance, force, gravity, mass, proportion

The electric force is a universal force that exists between any two charged objects. Opposite charges attract while like charges repel. The strength of the force is proportional to the charges, and, as with gravitation, inversely proportional to the square of the distance between them. 180 B (9-12)

attraction, distance, force, gravity, proportion, repulsion

Between any two charged particles, electric force is vastly greater than the gravitational force. Most observable forces such as those exerted by a coiled spring or friction may be traced to electric forces acting between atoms and molecules. 180 B (9-12)

coil, force, fractals, friction, gravity, scale

Electricity and magnetism are two aspects of a single electromagnetic force. Moving electric charges produce magnetic forces, and moving magnets produce electric forces. These effects help students to understand electric motors and generators. 180 B (9-12)

force, magnetism, motion, movement

Page 3

Conservation of energy and increase in disorder

teaching standard

spatial concepts

The total energy of the universe is constant. Energy can be transferred by collisions in chemical and nuclear reactions, by light waves and other radiations, and in many other ways. However, it can never be destroyed. As these transfers occur, the matter involved becomes steadily less ordered. 180 B (9-12)

collision, order, radiation, spatial interaction, universe, wave

All energy can be considered to be either kinetic energy, which is the energy of motion; potential energy, which depends on relative position; or energy contained by a field, such as electromagnetic waves.

field, kinetic, motion, position, wave

Heat consists of random motion and the vibrations of atoms, molecules, and ions. The higher the temperature, the greater the atomic or molecular motion. 180 B (9-12)

atom, molecule, motion, vibration

Everything tends to become less organized and less orderly over time. Thus, in all energy transfers, the overall effect is that energy is spread out uniformly. Examples are the transfer of energy from hotter to cooler objects by conduction, radiation, or convection and the warming of our surroundings when we burn fuels. 180 B (9-12)

Each kind of atom or molecule can gain or lose energy only in particular discrete amounts and thus can absorb and emit light only at wavelengths corresponding to these amounts. These wavelengths can be used to identify the substance. 180 B (9-12)

discrete, wave, wavelength

In some materials, such as metals, electrons flow easily, whereas in insulating materials such as glass they can hardly flow at all. Semiconducting materials have intermediate behavior. At low temperatures some materials become superconductors and offer no resistance to the flow of electrons. 181 B (9-12)

Properties and changes of properties in matter

teaching standard

spatial concepts

A substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances by using one or more of the characteristic properties. 154 B (5-8)

composition, density, mixture, separation, solubility, substance

Substances react chemically in characteristic ways with other substances to form new substances (compounds) with different characteristic properties. In chemical reactions, the total mass is conserved. Substances often are placed in categories or groups if they react in similar ways; metals is an example of such a group. 154 B (5-8)

categorization, compound, group, mass, placement

Chemical elements do not break down by normal laboratory reactions such as heating, exposure to electric current, or reaction with acids. There are more than 100 known elements that combine in a multitude of ways to produce compounds, which account for the living and nonliving substances that we encounter. 154 B (5-8)

composition, current, exposure, scale

Motion and forces

teaching standard

spatial concepts

The motion of an object can be described by its position, direction of motion, and speed. That motion can be measured and represented on a graph.

direction, graph, motion, object, position, representation, speed

An object that is not being subjected to a force will continue to move at a constant speed and in a straight line. 154 B (5-8)

force, line, motion, object, path, straight

If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude. Unbalanced forces will cause changes in the speed or direction of an object's motion. 154 B (5-8)

balance, direction, force, line, magnitude, motion, speed, straight

Transfer of energy

teaching standard

spatial concepts

Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways. 155 B (5-8)

light, motion, nucleus

Heat moves in predictable ways, flowing from warmer objects to cooler ones, until both reach the same temperature. 155 B (5-8)

flow, motion, spatial equilibrium

Light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection). To see an object, light from that object--emitted by or scattered from it--must enter the eye. 155 B (5-8)

Properties of objects and materials

teaching standard

spatial concepts

Objects have many observable properties, including size, weight, shape, color, temperature, and the ability to react with other substances. These properties can be measured using tools such as rulers, balances, and thermometers. 127 B (K-4)

balance, measurement, object, ruler, shape, size, thermometer

Objects are made of one or more materials, such as paper, wood, and metal. Objects can be described by the properties of the materials from which they are made ,and those properties can be used to separate or sort a group of objects or materials.

composition, group, object, separate, similarity, sort

Materials can exist in different states--solid, liquid, and gas. Some common materials, such as water, can be changed from one state to another by heating or cooling. 127 B (K-4)

transformation

Position and motion of objects

teaching standard

spatial concepts

The position of an object can be described by locating it relative to another object or the background.

background, location, object, position

An object's motion can be described by tracing and measuring its position over time. 127 B (K-4)

Structure of atoms

teaching standard

spatial concepts

Matter is made of minute particles called atoms, and atoms are composed of even smaller components. These components have measurable properties, such as mass and electrical charge. Each atom has a positively charged nucleus surrounded by negatively charged electrons. The electric force between the nucleus and electrons holds the atom together. 178 B (9-12)

atom, force, interaction, mass, measurement, nucleus, small, surround

The atom's nucleus is composed of protons and neutrons, which are much more massive than electrons. When an element has atoms that differ in the number of neutrons, these atoms are called different isotopes of the element. 178 B (9-12)

composition, mass, nucleus, size

The nuclear forces that hold the nucleus of an atom together, at nuclear distances, are usually stronger than the electric forces that would make it fly apart. Nuclear reactions convert a fraction of the mass of interacting particles into energy, and they can release much greater amounts of energy than atomic interactions. Fission is the splitting of a large nucleus into smaller pieces. Fusion is the joining of two nuclei at extremely high temperature and pressure, and is the process responsible for the energy of the sun and other stars. 178 B (9-12)

bond, distance, fission, force, nucleus, scatter, size

Radioactive isotopes are unstable and undergo spontaneous nuclear reactions, emitting particles and/or wavelike radiation. The decay of any one nucleus cannot be predicted, but a large group of identical nuclei decay at a predictable rate. This predictability can be used to estimate the age of materials that contain radioactive isotopes. 178 B (9-12)

decay, emission, nucleus, radiation, rate, wave

Structure and properties of matter

teaching standard

spatial concepts

Atoms interact with one another by transferring or sharing electrons that are furthest from the nucleus. These outer electrons govern the chemical properties of the element. 178 B (9-12)

An element is composed of a single type of atom. When elements are listed in order according to the number of protons (called the atomic number), repeating patterns of physical and chemical properties identify families of elements with similar properties. This 'Periodic Table' is a consequence of the repeating pattern of outermost electrons and their permitted energies. 178 B (9-12)

outer, pattern, representation, spatialization

Bonds between atoms are created when electrons are paired up by being transferred or shared. A substance composed of a single kind of atom is called an element. The atoms may be bonded together into molecules or crystalline solids. A compound is formed when two or more kinds of atoms bind together chemically. 179 B (9-12)

atom, atomicity, bond, composition, crystalline, interaction, pairing

The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them. 179 B (9-12)

Solids, liquids, and gases differ in the distances and angles between molecules or atoms and therefore the energy that binds them together. In solids the structure is nearly rigid; in liquids molecules or atoms move around each other but do not move apart; and in gases molecules or atoms move almost independently of each other and are mostly far apart. 179 B (9-12)

Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, including synthetic polymers, oils, and the large molecules essential to life. 179 B (9-12)

atom, bond, branching, chain, molecule, network, ring

Page 2

Biological evolution

teaching standard

spatial concepts

The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms. 185 C (9-12)

niche

Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms. 185 C (9-12)

fossil, similarity

The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors. 185 C (9-12)

scale

Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification. 185 C (9-12)

classification, group, hierarchy, similarity

Interdependence of organisms

teaching standard

spatial concepts

The atoms and molecules on the earth cycle among the living and nonliving components of the biosphere. 186 C (9-12)

atom, composition, cycle, interaction, molecule

Energy flows through ecosystems in one direction, from photosynthetic organisms to herbivores to carnivores and decomposers. 186 C (9-12)

direction, flow

Organisms both cooperate and compete in ecosystems. The interrelationships and interdependencies of these organisms may generate ecosystems that are stable for hundreds or thousands of years. 186 C (9-12)

ecosystem, environment, interrelationship, size, stability

Living organisms have the capacity to produce populations of infinite size, but environments and resources are finite. This fundamental tension has profound effects on the interactions between organisms. 186 C (9-12)

environment, finite, infinite, size

Human beings live within the world's ecosystems. Increasingly, humans modify ecosystems as a result of population growth, technology, and consumption. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is threatening current global stability, and if not addressed, ecosystems will be irreversibly affected. 186 C (9-12)

Matter, energy, and organization in living systems

teaching standard

spatial concepts

All matter tends toward more disorganized states. Living systems require a continuous input of energy to maintain their chemical and physical organizations. With death, and the cessation of energy input, living systems rapidly disintegrate. 186 C (9-12)

disintegration, order, organization, site, state

Page 3

Conservation of energy and increase in disorder

teaching standard

spatial concepts

The total energy of the universe is constant. Energy can be transferred by collisions in chemical and nuclear reactions, by light waves and other radiations, and in many other ways. However, it can never be destroyed. As these transfers occur, the matter involved becomes steadily less ordered. 180 B (9-12)

collision, order, radiation, spatial interaction, universe, wave

All energy can be considered to be either kinetic energy, which is the energy of motion; potential energy, which depends on relative position; or energy contained by a field, such as electromagnetic waves.

field, kinetic, motion, position, wave

Heat consists of random motion and the vibrations of atoms, molecules, and ions. The higher the temperature, the greater the atomic or molecular motion. 180 B (9-12)

atom, molecule, motion, vibration

Everything tends to become less organized and less orderly over time. Thus, in all energy transfers, the overall effect is that energy is spread out uniformly. Examples are the transfer of energy from hotter to cooler objects by conduction, radiation, or convection and the warming of our surroundings when we burn fuels. 180 B (9-12)

Each kind of atom or molecule can gain or lose energy only in particular discrete amounts and thus can absorb and emit light only at wavelengths corresponding to these amounts. These wavelengths can be used to identify the substance. 180 B (9-12)

discrete, wave, wavelength

In some materials, such as metals, electrons flow easily, whereas in insulating materials such as glass they can hardly flow at all. Semiconducting materials have intermediate behavior. At low temperatures some materials become superconductors and offer no resistance to the flow of electrons. 181 B (9-12)

Structure and function in living systems

teaching standard

spatial concepts

Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems. 156 C (5-8)

All organisms are composed of cells--the fundamental unit of life. Most organisms are single cells; other organisms, including humans, are multicellular. 156 C (5-8)

cell, composition, multicellular, unit

Cells carry on the many functions needed to sustain life. They grow and divide, thereby producing more cells. This requires that they take in nutrients, which they use to provide energy for the work that cells do and to make the materials that a cell or an organism needs. 156 C (5-8)

absorption, divide, division, grow, growth

Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole. 156 C (5-8)

The human organism has systems for digestion, respiration, reproduction, circulation, excretion, movement, control and coordination, and for protection from disease. These systems interact with one another. 156 C (5-8)

coordination, excretion, interaction, motion, movement, system

Disease is a breakdown in structures or functions of an organism. Some diseases are the result of intrinsic failures of the system. Others are the result of damage by infection by other organisms. 157 C (5-8)

decomposition, infection, structure

Reproduction is a characteristic of all living systems; because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually. 157 C (5-8)

teaching standard

spatial concepts

In many species, including humans, females produce eggs and males produce sperm. Plants also reproduce sexually--the egg and sperm are produced in the flowers of flowering plants. An egg and sperm unite to begin the development of a new individual. That new individual receives genetic information from its mother (via the egg) and its father (via the sperm). Sexually produced offspring never are identical to either of their parents. 157 C (5-8)

production, receive, unite, uniting

Every organism requires a set of instructions for specifying its traits. Heredity is the passage of these instructions from one generation to another. 157 C (5-8)

passage

Hereditary information is contained in genes, located in the chromosomes of each cell. Each gene carries a single unit of information. An inherited trait of an individual can be determined by one or many genes, and a single gene can influence more than one trait. A human cell contains many thousands of different genes. 157 C (5-8)

containment, location, transport

Reproduction and heredity

teaching standard

spatial concepts

In many species, including humans, females produce eggs and males produce sperm. Plants also reproduce sexually--the egg and sperm are produced in the flowers of flowering plants. An egg and sperm unite to begin the development of a new individual. That new individual receives genetic information from its mother (via the egg) and its father (via the sperm). Sexually produced offspring never are identical to either of their parents. 157 C (5-8)

production, receive, unite, uniting

Every organism requires a set of instructions for specifying its traits. Heredity is the passage of these instructions from one generation to another. 157 C (5-8)

passage

Hereditary information is contained in genes, located in the chromosomes of each cell. Each gene carries a single unit of information. An inherited trait of an individual can be determined by one or many genes, and a single gene can influence more than one trait. A human cell contains many thousands of different genes. 157 C (5-8)

containment, location, transport

Page 2

Reproduction and heredity

teaching standard

spatial concepts

The characteristics of an organism can be described in terms of a combination of traits. Some traits are inherited and others result from interactions with the environment. 157 C (5-8)

combination, environment, interaction

Regulation and behavior

teaching standard

spatial concepts

All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing external environment. 157 C (5-8)

Behavior is one kind of response an organism can make to an internal or environmental stimulus. A behavioral response requires coordination and communication at many levels, including cells, organ systems, and whole organisms. Behavioral response is a set of actions determined in part by heredity and in part from experience. 157 C (5-8)

An organism's behavior evolves through adaptation to its environment. How a species moves, obtains food, reproduces, and responds to danger are based in the species' evolutionary history. 157 C (5-8)

behavior, environment, motion, movement

Population and ecosystems

teaching standard

spatial concepts

A population consists of all individuals of a species that occur together at a given place and time. All populations living together and the physical factors with which they interact compose an ecosystem.

Populations of organisms can be categorized by the function they serve in an ecosystem. Plants and some micro-organisms are producers--they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem. 157 C (5-8)

ecosystem, interaction, scale, web

For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs. 158 C (5-8)

ecosystem, enter, exit, sunlight, transfer, web

The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem. 158 C (5-8)

Diversity and adaptations of organisms

teaching standard

spatial concepts

Millions of species of animals, plants, and micro-organisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry. 158 C (5-8)

internal, scale, structure, unity

Page 3

Diversity and adaptations of organisms

teaching standard

spatial concepts

Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment. 158 C (5-8)

environment, structure

Extinction of a species occurs when the environment changes and the adaptive characteristics of a species are insufficient to allow survival. Fossils indicate that many organisms that lived long ago are extinct. Extinction of species is common; most of the species that have lived on the earth no longer exist. 158 C (5-8)

Characteristics of organisms

teaching standard

spatial concepts

Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients, and light. Organisms can survive only in environments in which their needs can be met. The world has many different environments, and distinct environments support the life of different types of organisms. 129 C (K-4)

environment, world

Each plant or animal has different structures that serve different functions in growth, survival, and reproduction. For example, humans have distinct body structures for walking, holding, seeing, and talking. 129 C (K-4)

growth, holding, seeing, structure, walking

The behavior of individual organisms is influenced by internal cues (such as hunger) and by external cues (such as a change in the environment). Humans and other organisms have senses that help them detect internal and external cues. 129 C (K-4)

containment, environment, external, internal

Life cycles of organisms

teaching standard

spatial concepts

Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. 129 C (K-4)

cycle, development

Plants and animals closely resemble their parents. 129 C (K-4)

resemblance

Many characteristics of an organism are inherited from the parents of the organism, but other characteristics result from an individual's interactions with the environment. Inherited characteristics include the color of flowers and the number of limbs of an animal. Other features, such as the ability to ride a bicycle are learned through interactions with the environment and cannot be passed on to the next generation. 129 C (K-4)

environment, interaction

Organisms and environments

teaching standard

spatial concepts

All animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat the plants. 129 C (K-4)

An organism's patterns of behavior are related to the nature of that organism's environment, including the kinds and numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment. When the environment changes, some plants and animals survive and reproduce, and others die or move to new locations. 129 C (K-4)

Energy in the earth system

teaching standard

spatial concepts

Earth systems have internal and external sources of energy, both of which create heat. The sun is the major external source of energy. Two primary sources of internal energy are the decay of radioactive isotopes and the gravitational energy from the earth's original formation.

decay, external, formation, gravity, internal, source

The outward transfer of earth's internal heat drives convection circulation in the mantle that propels the plates comprising earth's surface across the face of the globe. 189 D (9-12)

Heating of earth's surface and atmosphere by the sun drives convection within the atmosphere and oceans, producing winds and ocean currents. 189 D (9-12)

convection, current, surface, wind, within

Global climate is determined by energy transfer from the sun at and near the earth's surface. This energy transfer is influenced by dynamic processes such as cloud cover and the earth's rotation, and static conditions such as the position of mountain ranges and oceans. 189 D (9-12)

Geochemical cycles

teaching standard

spatial concepts

The earth is a system containing essentially a fixed amount of each stable chemical atom or element. Each element can exist in several different chemical reservoirs. Each element on earth moves among reservoirs in the solid earth, oceans, atmosphere, and organisms as part of geochemical cycles. 189 D (9-12)

cycle, motion, movement, quantity, reservoir, system

Movement of matter between reservoirs is driven by the earth's internal and external sources of energy. These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life .

Origin and evolution of the earth system

teaching standard

spatial concepts

The sun, the earth, and the rest of the solar system formed from a nebular cloud of dust and gas 4.6 billion years ago. The early earth was very different from the planet we live on today. 189 D (9-12)

formation, nebular, solar system, system

Geologic time can be estimated by observing rock sequences and using fossils to correlate the sequences at various locations. Current methods include using the known decay rates of radioactive isotopes present in rocks to measure the time since the rock was formed. 189 D (9-12)

Interactions among the solid earth, the oceans, the atmosphere, and organisms have resulted in the ongoing evolution of the earth system. We can observe some changes such as earthquakes and volcanic eruptions on a human time scale, but many processes such as mountain building and plate movements take place over hundreds of millions of years. 189 D (9-12)

Evidence for one-celled forms of life--the bacteria--extends back more than 3.5 billion years. The evolution of life caused dramatic changes in the composition of the Earth's atmosphere, which did not originally contain oxygen. 190 D (9-12)

cell, composition

Page 2

Origin and evolution of the universe

teaching standard

spatial concepts

The origin of the universe remains one of the greatest questions in science. The 'big bang' theory places the origin between 10 and 20 billion years ago, when the universe began in a hot dense state; according to this theory, the universe has been expanding ever since. 190 D (9-12)

density, expansion

Early in the history of the universe, matter, primarily the light atoms hydrogen and helium, clumped together by gravitational attraction to form countless trillions of stars. Billions of galaxies, each of which is a gravitationally bound cluster of billions of stars, now form most of the visible mass in the universe. 190 D (9-12)

attraction, bond, clump, cluster, formation, gravity, mass, matter

Stars produce energy from nuclear reactions, primarily the fusion of hydrogen to form helium. These and other processes in stars have lead to the formation of all the other elements. 190 D (9-12)

Structure of the earth system

Global patterns of atmospheric movement influence local weather. Oceans have a major effect on climate, because water in the oceans holds a large amount of heat. 160 D (5-8)

containment, formation, global, local, movement, pattern

Living organisms have played many roles in the earth system, including affecting the composition of the atmosphere, producing some types of rocks, and contributing to the weathering of rocks. 160 D (5-8)

composition, weathering

Lithospheric plates on the scales of continents and oceans constantly move at rates of centimeters per year in response to movements in the mantle. Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions. 160 D (5-8)

Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion. 160 D (5-8)

Some changes in the solid earth can be described as the 'rock cycle.' Old rocks at the earth's surface weather, forming sediments that are buried, then compacted, heated, and often recrystallized into new rock. Eventually, these new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues. 160 D (5-8)

buried, compaction, cycle, force, formation, motion, plate, surface

Soil consists of weathered rocks, decomposed organic material from dead plants, animals, and bacteria. Soils are often found in layers, with each having a different chemical composition and texture. 160 D (5-8)

composition, layer, texture

Water, which covers the majority of the earth's surface, circulates through the crust, oceans, and atmosphere in what is known as the 'water cycle.' Water evaporates from the earth's surface, rises and cools as it moves to higher elevations, condenses as rain or snow, and falls to the surface where it collects in lakes, oceans, soil, and in rocks underground. 160 D (5-8)

The atmosphere is a mixture of nitrogen, oxygen, and trace gases that include water vapor. The atmosphere has different properties at different elevations. 160 D (5-8)

elevation, mixture

Page 2

Structure of the earth system

teaching standard

spatial concepts

Clouds, formed by the condensation of water vapor, affect weather and climate. 160 D (5-8)

condensation, formation

Earth's history

teaching standard

spatial concepts

The Earth processes we see today, including erosion, movement of lithospheric plates, and changes in atmospheric composition, are similar to those that occurred in the past. Earth history is also influenced by occasional catastrophes, such as the impact of an asteroid or comet. 160 D (5-8)

change, composition, erosion, impact, motion, movement, past, plate

Fossils provide important evidence of how life and environmental conditions have changed. 160 D (5-8)

environment, fossil

Earth in the solar system

teaching standard

spatial concepts

The earth is the third planet from the sun in a system that includes the moon, the sun, eight other planets and their moons, and smaller objects, such as asteroids and comets. The sun, an average star, is the central and largest body in the solar system. 160 D (5-8)

centrality, location, orbit, order, planet, position, size, sun

Most objects in the solar system are in regular and predictable motion. Those motions explain such phenomena as the day, the year, phases of the moon, and eclipses. 160 D (5-8)

eclipse, motion, object, phase

Gravity is the force that keeps planets in orbit around the sun and governs the rest of the motion in the solar system. Gravity alone holds us to the earth's surface and explains the phenomena of the tides. 161 D (5-8)

attraction, force, gravity, motion, orbit, surface, tide, tides

The sun is the major source of energy for phenomena on the earth's surface, such as growth of plants, winds, ocean currents, and the water cycle. Seasons result from variations in the amount of the sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and the length of the day. 161 D (5-8)

Properties of earth materials

teaching standard

spatial concepts

Earth materials are solid rocks and soils, water, and the gases of the atmosphere. These varied materials have different physical and chemical properties, which make them useful in different ways, for example, as building materials, as sources of fuel, or for growing the plants we use as food. Earth materials provide many of the resources that humans use. 134 D (K-4)

Soils have properties of color and texture, capacity to retain water, and ability to support the growth of many kinds of plants, including those in our food supply. 134 D (K-4)

growth, property, texture

Fossils provide evidence about the plants and animals that lived long ago and nature of the environment at that time. 134 D (K-4)

environment, evidence, fossil, timeline

Objects in the sky

teaching standard

spatial concepts

The sun, moon, stars, clouds, birds, and airplanes all have properties, locations, and movements that can be observed and described. 134 D (K-4)

location, movement, property

The sun provides the light and heat necessary to maintain the temperature of the earth. 134 D (K-4)

position

Changes in the sky

teaching standard

spatial concepts

The surface of the earth changes. Some changes are due to slow processes, such as erosion and weathering, and some changes are due to rapid processes such as landslides, volcanoes, and earthquakes. 134 D (K-4)

Weather changes from day to day and over the seasons. Weather can be described by measurable quantities, such as temperature, wind direction and speed, and precipitation. 134 D (K-4)

direction, measurement, movement, precipitation, speed, temperature

Objects in the sky have patterns of movement. The sun, for example, appears to move across the sky in the same way every day, but its path changes slowly over the seasons. The moon moves across the sky on a daily basis much like the sun. The observable shape of the moon changes from day to day in a cycle that lasts about a month. 134 D (K-4)